1. Field of the Invention:
The present invention relates to an ignition coil unit having at least one coil assembly directly connected to each spark plug provided for one of a plurality of cylinders of an internal combustion engine.
2. Description of the Prior Art:
There has been known an ignition system in which one ignition coil unit is provided for each of a plurality of cylinders of an internal combustion engine and directly connected to a spark plug of each respective cylinder (e.g., Journal of Nippondenso Technical Disclosure No. 75-017, published Nov. 15, 1990).
In recent years, attempts have been made to mount such an ignition system in a compact and small-displacement internal combustion engine, but no one was successful because the compact and small-displacement internal combustion engine can only provide a small space between opposed cylinder head covers, which space is insufficient to allow installation of the ignition coil unit.